Optimal Power Flow and Short-Circuit Analysis in Hybrid Renewable-Powered DC Microgrids using Modular Multilevel Converters

Modern power systems require an increased use of renewable energy, which drives the acceptance of DC microgrids because they reduce conversion needs and directly support battery storage for improved performance. Combining several renewable energy sources and fault protection reliability proves to be a significant operational challenge. This paper examines an integrated approach to studying optimal power flow and short-circuit analysis within renewable energy-powered DC microgrids incorporating a modular multilevel converter (MMC). The main goal involves achieving optimal daily decision-making for solar and wind power, battery capacity, and safeguarding the system against excessive transient currents. The model has been set up in MATLAB to integrate critical components like charge restrictions of battery-powered generation, real-time generation capacity, and MMC-defined voltage and current constraints. An optimum power flow solver sets dispatch levels to minimise losses and hold the DC bus at stable levels. Short-circuit conditions of fault current reactions and voltage drop examinations were also performed after defining the dispatch setpoint at which the MMC submodule bypass acted as a protective device. Most power generation from renewable sources minimises battery intervention, considering that the device offers a lot of current assistance for faults in the event of DC faults. The holistic approach involved both an economic analysis and the nature of a fault response, which proved that the protective parameters needed to be directly analysed, as well as the operational effectiveness.